Many devices and systems include a number of different types of sensors that perform various monitoring and/or control functions. Advancements in micromachining and other microfabrication processes have enabled the manufacturing of a wide variety of micro-electromechanical systems (MEMS). In recent years, many of the sensors that are used to perform monitoring and/or control functions have been implemented into MEMS devices.
One particular type of MEMS device is an accelerometer. A MEMS accelerometer may be formed in a silicon-on-insulator (“SOI”) wafer that includes a handle layer, an insulating sacrificial layer comprising oxide overlying the handle layer, and an active layer overlying the insulating layer. The SOI MEMS accelerometer typically includes a proof mass that is formed in the active layer. A portion of the proof mass may be anchored to a section of the wafer via a portion of the insulating layer, while another portion of the proof mass may be suspended over the wafer, usually via a set of compliant beam springs. The proof mass moves when the MEMS accelerometer experiences acceleration, and the movement is converted via electronics into a signal having a parameter magnitude (e.g. voltage, current, frequency, etc.) that is dependent on the acceleration.
Typically, a MEMS sensor is subjected to rigorous testing before being shipped to a customer. The testing may include dropping the sensor from a predetermined height. This test simulates a mechanical shock that may be experienced when the customer handles the device. In most cases, currently configured MEMS sensors are sufficiently robust to withstand such a drop test. However, in other cases, the test may damage the MEMS sensor. In particular, the portion of the proof mass that is anchored to the wafer may become separated from the handle wafer. As a result, the MEMS sensor may become inoperable.
Accordingly, it is desirable to provide a MEMS sensor that is sufficiently robust to withstand stresses that may be applied thereto. In addition, it is desirable to have a simple and relatively inexpensive process for manufacturing the desired MEMS sensor that does not require additional equipment or processes. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.